1. Field of the Invention
The present invention relates to a current sensor having an element made of amorphous magnetic metal.
2. Description of the Related Art
Various method of detecting electrical currents flowing in circuits are known. The typical ones of these methods are: voltage-drop detecting method, magnetic-field detecting method, and current-transformer method. In the voltage-drop method, the voltage drop across a resistor connected to a circuit is detected, thereby to determine the current flowing in the circuit. In the magnetic-field detecting method, a Hall element is used to determine the current flowing through the circuit. In the current transformer method, the variation of magnetic fluxes is utilized in order to determine the current flowing in this circuit.
With the voltage-drop detecting method, it is difficult to ensure sufficient insulation of the measuring system when the line voltage across the circuit is relatively high. Hence, this method can apply to low-voltage circuits only. Another problem inherent in this method is the heat generated by the resistor, which is enormous when a great current flows in the circuit. The magnetic-field detecting method has also a problem, i.e., the temperature drift of the Hall element. This temperature drift makes it essentially impossible to determine the current in the circuit, with sufficiently high accuracy. The magnetic-field detecting method, in which the current in the circuit is determined from the variation in the intensity of magnetic fluxes, is disadvantageous in that the current determined is not always correct.
As can by understood from the above, with the conventional current-detecting method it is impossible to measure the direct or alternating current flowing in a circuit and ranging over a broad range, always with ease and accuracy.